Linear action hygrometer

ABSTRACT

This invention relates to a linear action hygrometer utilizing two or more xeric elements which are sensitive to changes in vapor pressure, i.e., relative humidity, and which bend in a single plane from substantially straight when soaked to a substantial arc when dry, whereby the combined effect of the various elements can give a greater force and move a greater distance than was possible with a single such element.

United States Patent [1 1 Renholts Mar. 19, 1974 1 LINEAR ACTION HYGROMETER [75] Inventor: Roy J. Renholts, Oakland, Calif.

[73] Assignee: Hygrometrics, Inc., Oakland, Calif.

[22] Filed: Jan. 31, 1972 [21] Appl. No.: 221,891

[52] 11.5. C1. 73/337, 73/336 [51] Int. Cl. ..G01w1/00, G01n 19/10 [58] Field of Search 73/337, 337.5, 363.3, 363.1

[56] References Cited UNITED STATES PATENTS 177,793 5/1876 Blake 73/3631 3,608,377 9/1971 Fenner..... 73/3375 1.995.107 3/1935 Schlatter t 73/337 1.777.000 9/1930 Kasser 73/3631 Cormanl 73/3631 Dumm 73/3633 Primary Examiner-RichardC. Queisser Assistant Examiner-Denis E. Corr Attorney, Agent, or Firm-Robyn Wilcox [5 7] ABSTRACT This invention relates to a linear action hygrometer utilizing two or more xeric elements which are sensitive to changes in vapor pressure, i.e., relative humidity, and which bend in a single plane from substantially straight when soaked to a substantial are when dry, whereby the combined effect of the various elements can give a greater force and move a greater distance than was possible with a single such element.

6 Claims, 9 Drawing Figures LINEAR ACTION HYGROMETER BACKGROUND OF THE INVENTION The linear action hygrometer of the present invention utilizes a partially bridled xeric element, such as the one described in connection with FIGS. 6 to 8, inclusive, of the copending application of Fenner and Martin entitled XERIC ELEMENT AND METHOD OF PREPARING THE SAME, filed on June 8, 1970, Ser. N0..44,626, now US. Pat. No. 3,608,377. Briefly, the xeric element comprises: (1) a resilient metal saddle, preferably of beryllium copper of a thickness of .001 inch and preferably 14 millimeters in length and 2 millimeters in width; the two ends of the strip being bent back upon a common face to form pockets at each end having a length of 2 millimeters, leaving the overall length of the element, or xeric chip, at millimeters; and (2) a moisture-sensitive element, which is the rib, or spine of a seed-throwing arm which forms an extension of the seed pod of a plant of the genus Geranium, such as Geranium dissectum, Geranium Richardsonii, Geranium caespitosum, or Geranium eriostomas. The spine is prepared as described in said application. The throwing arm, inits natural state (when dry), assumes a flat spiral form extending through an arc of between 450 and 540, depending primarily upon the dryness of the environment, but somewhat upon the particular species of plant used. When saturated with water, these ribs are straight and strong; and when thoroughly dry, form a spiral lying in a substantially single plane extending through an arc of about one and one-half turns. In my preferred xeric element, I take a length of 9 millimeters of such a rib for use on a moisture-sensitive member and place one or more (preferably two) such elements in the metallic saddle and fasten them, at their ends only, in the pockets of the saddle. When the vegetable fibers are permitted to dry, their warp force bends the metal plate from the form shown in FIGS. 6 and 8 herein to that shown in FIGS. 7 and 9, thereby forming an arc, the ends of which lie in an angle of about 60 with respect to each other. As the elements dry, they exert a constant warp force upon the metal member, that causes it to bend in equal increments directly proportional to the relative humidity of the environment; and conversely, when they are moist, they straighten and the chip will resume its original straight form (likewise proportional to the humidity of the environment). It should be noted that the xeric elements, in their dry and natural state, form a helix lying in a single plane, so that the metallic saddle is subjected to a simple bending action only and not to a complicated twisting.

More specifically, the present invention relates to a method, or mounting, of two or more such chips, so as to multiply the amount of movement, as well as the force provided, over that of a single element, or chip. If two such elements are used side by side in a single saddle in accordance with the teaching of the present invention, the force will be twice as great-as that of a single chip. Any desired linear movement is accomplished by stacking the xeric chips back-to-back or face-to-face on opposite sides of a disk, so that the total movement generated is equal to the total of the individual movements of the chips. The present mounting also provides means for quickly and easily adjusting the movement of the movable member, as there will necessarily be slight variations in the force of magnitude of movement of individual fibers and hence an instrument using such fibers should always be checked and often needs to be calibrated before use.

It is a primary object of the present invention to provide a linear action hygrometer utilizing two or more xeric elements which bend in a single plane according to the vapor pressure, or humidity, of the environment whereby a greater magnitude of movement can be secrured and also a greater force.

Another object of the invention is to provide a frictionless actuating member.

Another object of the present invention is to provide a hygrometer that can be quickly and easily adjusted to provide sensitive and accurate measurement irrespective of slight variations in the strength of the xeric fibers used.

Another object of the invention is to utilize the fiber in a manner so as to form an arch with the pressure applied at the apex. The force is thus transmitted down the two legs of the arch, relieving a flexural strain on the fiber which is inherent in the other design where one end of the fiber is fixed and the other extremity is used for force. The arch is particularly pronounced when the fiber is in the dry state. This is an advantage since the fibers must overcome the greatest spring pressure when the mechanism is registering dry.

It is another important object of the present invention to provide a hygrometric device utilizing two or more xeric elements of the class described which move the primary member in a linear direction whereby the force and magnitude of movement of a plurality of such elements can be combined; and in which the linear movement of the primary member can be applied to a rotating member which is substantially friction-free.

These and other objects of the present invention will be apparent from the specification which follows, taken in connection with the accompanying drawings in which:

FIG. 1 is a side view of the device of the xeric elements;

FIG. 2 is a front view of one of the xeric elements;

FIGS. 3, 4 and 5 are modifications of the disk interposed between the two xeric elements shown in FIG. 1;

FIGS. 6 and 7 show the movement of the xeric element when going from the saturatedcondition shown in FIG. 6 to the dry condition shown in FIG. 7; and

FIGS. 8 and 9' show similar movement of a single xeric element when applied to a disk, the edges of which are slightly beveled.

The device of the present invention is mounted in a relatively rigid and strong frame comprising the end pieces 21, 22, base 23 and top member 24. Each of the two end pieces have rigidly mounted thereon a guide plate 25 and 26, respectively, each of which, in the embodiment shown, is provided with a square aperture 32. A hollow square shaped bar, or tube, 29 lies within the apertures, which are considerably larger than the bar, as the apertures are not intended to be bearings for the bar but as guides therefor. Each of the guide plates 25, 26 is respectively affixed to its associated end piece 21, 22 by suitable bolts 27, 28. The end piece 21 also carries a bracket member 30 extending parallel to the axis of the tube 29. The central section of the tube 29 has one side ground away, as at 31, to permit the wire to pass around a rotatable member 45. as described hereinafter.

The wire 35 is attached at one end to the square bar 29 as by looping through a hole 36, as shown. It passes around the rotatable member 45 and thence to one end of a spring 37 which is pinned, as by pin 38, to the other end of the bar 29.

The rotatable assembly 45 comprises a hollow shaft 46, the central portion of which is considerably enlarged as is shown at 47. A pair of conical nuts 48 and 49 are threaded onto the shaft 46, their respective conical faces being truncated and facing each other across the central portion 47 of the shaft 46. A split bushing 51 surrounds the central portion 47 of the shaft 46, its ends abutting against the opposed conical faces of the two nuts 48 and 49 and, among other things, will act as a lock washer to keep the conical nuts from turning. The wire 35, which connects the two ends of the hollow square bar 29, goes around the split bushing 51 and around a set screw 52, as shown in FIG. 1. A nut 50 is also threaded to theshaft 46 and is used to hold a pointer 53 in place.

The rotatable assembly 45 is mounted on a taut wire 60, one end of which is passed through a pair of holes, not shown, in the side frame 23 and thence caught by a locking screw 61. The wire 60 passes through the hollow shaft 46 and'the other end is fastened to the side frame 24 by an adjustable anchor comprising a threaded hollow screw 62, the inner end of which is provided with an integral nut 63 and the other end of which passes through an aperture, not shown, in the top frame member 24 and then through a shoulder nut 65 on the outside of the frame. The hollow threaded member 62 is locked in any adjustable position by a lock nut 64. The wire 60 can be fastened to the outer end of the hollow screw 62 by any suitable means, such as being looped over a pin, not shown, which engages theouter face of that hollow screw. By turning the hollow screw 62 or the nut 65, the wire 60 can be tightened under considerable force and becomes very taut. The set screw 52, already mentioned as having the wire 35 looped around it, is tightened to to tightly hold the wire 60, so that the wire 60 supports the entire assembly 45 in the desired position. It can be noted at this point that movement of the hollow square bar 29, through the movement of the bow spring wire 35, will rotate the rotatable assembly 45, and since there are no bearings, no friction will be involved in such movement. In such movement, the wire 60 will twist. The force of the torq we in the wire 60, combined with that of the tension spring 37, biases the hollow bar 29 (to the left in FIG. 1) against the force of two xeric elements 70, 71.

Constant pressure must be applied by the bar 29 against the chips 70, 71 so that as the fibers straighten in a humid environment, the needle will return to zero. If, for example, the instrument were mounted with the end piece 22 down, so that the force of gravity was pulling the entire linearly moving assembly away from the position, the instrument can be corrected to a true reading by loosening the lock nut 64 and turning hollow screw 62 and thereby twist wire 60 (from the force of friction which will hold the pin over which the wire looped against the outer end of the screw). Such twisting of the wire will cause a torque within the wire, to

turn the spindle 45 and pull the bar 29 upwardly against the chips 70, 71. Thus, sufficient pressure can be maintained regardless of the mounting of the instrument, as the weight of the bar and its related parts can always be equalized by the torque of wire 60.

The xeric elements are shown in plan view in FIG. 2 and comprise a thin metallic strip 72, preferably formed of beryllium copper. A pair of xeric fibers 73, 74 lie against the face of the sheet 72 and their ends are fastened in the tumed-over end 75 by any suitable means. In this embodiment, the saddle 72 is provided with a central aperture 78 adapted to encircle a pin 85, to be described in the next paragraph. The two xeric elements 70 and 71, comprising the saddle 72 and their fibers 73, 74, have each of their ends forced into plastic bearing members 76 and 77 which, incidentally, may be in the cup-like ends of the saddle by their ends only.

The two xeric elements 70, 71 are threaded upon the pin 85 with a plastic disk 86 being interposed between them, the xeric fibers 73 and 74 lying facing the disk 86. The pin 85 has an enlarged threaded end 87 which is threaded into a suitable aperture in the perpendicularly turned end of the bracket'30. The end of the enlarged threaded end 87 of the pin 85 forms a stop, or

shoulder, 88, which bears against the back, or metallic,

side of the xeric chip 71, while the backside of the xeric chip bears against the'end of the hollow bar 29. The pin is of sufficient length to enter into the hollow bar 29 for a relatively large distance, even when the xeric elements 70, 71 are curved to their extreme position of absolute dryness. Thus, neither of the xeric elements can be lost from its position against an intervening disk 86. The threaded pin 87 can be adjusted to force the chips 70, 71 against the bar 29, and hence is used to set the pointer 53 to its 0 setting.

The relative positions of the two xeric chips 70, 71 against the intermediate disk 86 is shown in FIGS. 6 and 7 FIG. 6 showing the related elements in a saturated condition, and FIG. 7 showing them in an extremely dry condition. In these figures the enlarged end 87 of the pin 85 and the hollow bar 29 are omitted. Generally, these chips move about .065 inch from the extremely wet position of FIG. 6 to the dry position of FIG. 7. Thus, the total distance that the two assemblies move from the completely wet to completely dry is .130 inch. If greater movement is desired, additional two-element assemblies can be placed upon the single pin 85. If there were four chips, then there would be .260 inch movement from wet to dry. At the same time, the force applied by these elements is multiplied by the same number, so that considerable torque is applied to the rotatable assembly 45.

The adjustment of the conical nut 48 will obviously change the diameter of the split sleeve, or bushing, 51. In the assembly which is usually used, the diameter of the split sleeve is approximately .250 inch. This diameter, however, can be changed by a slight movement of conical nut 48 upon hollow shaft 46 to compensate for variations in movement of the chips 70,71. A.003 inch change in the diameter of the spindle will cause a 1 of change of the pointer on the dial plate having an arc of 5.2 inches. On occasions where the fiber movement is extreme in either direction, movement may be compensated for by various configurations of the cam disks, as described hereafter. However, as indicated above, the total magnitude of the movement of the two xeric chips 70, 71 is approximately .130 inch. When this is multiplied by 20, by the turn of the spindle 45, it gives 2.6 inches sweep of the pointer 53, and four such chips give a movement over an arc of 5.2 inches.

FIGS; 8 and 9 are similar to FIGS. 6 and 7, except that the intermediate disk 96 is beveled as at 97 at an angle of9. A 9 angle affords a rise of .008 inch in going from the wet position of FIG. 8 to the dry position of FIG. 9. If four chips with two disks are'used, they will give a total of .032 inch of movement in addition to the .130 inch secured on the flat disk 86 in FIGS. 6 and 7. This is more than 12 of needle movement and affords an easy way of adjusting the variations in the movement of the fibers, so that a standard dial and pointer arrangement can be used. Since the individual fibers vary greatly in their total movement, the selection of a combination of cam disks enables the acceptance of almost any fiber to a standard dial. FIGS. 3, 4 and 5 show a few configurations that are possible to correct for a true needle reading. For example, if instead of a straight bevel of the disk, as shown in FIGS. 8 and 9, a disk 99 (FIG. 3) has a concave, or indented, radius 100, the movement of the xeric elements will be slower at the wet end of the reading and faster at the dry. Or, for example, a disk 103 (FIG. 4) is provided with a convex, or reverse, radius 104 which will provide for a rapid movement at the dry end and a slower one at the wet. Finally, it is possible for a disk 107 (FIG. 5) to be provided with both convex and concave radii 108. Thus, an assortment of angles on one or both sides of the disk gives an endless varietyof dimensions which can adjust the idiosyncrasies of the individual fibers to a standard dial. So far, experience has shown that the characteristic of fiber movement is consistent but that the magnitude of such movement varies slightly from fiber to fiber, and this variation can be easily modified by the linear action of the plurality of chips herein shown and described. It can be noted that any angle of the bevel can be used as long as it is not too steep to interfere with the free movement of the chips 70, 71.

It is believed that the present device has many advantages over prior art in that a greater magnitude of movement can be secured by the use of two or more xeric chips and the movement of the pointer of a gauge can be readily changed to correlate the reading from a particular set of xeric elements by use of the cams, or cam disks, as above mentioned, or by the adjustment of the rotatable assembly 45 to increase or decrease the diameter of the split sleeve. It is also believed that many modifications can be made in the present device to those skilled in the art, and all such modifications are intended to lie within the scope of the following claims.

I claim: 7

1. A linear action hygrometer comprising:

a. a plurality of xeric elements, said xeric elements including a saddle formed of thin resilient metal, a moisture-sensitive fiber taken from the seed pod of the plant of the genus Geranium, and means for securing the ends of the fiber to the metallic saddle;

b. a pin for holding a plurality of said elements, said elements being slidably positioned on said pin in face-to-face relationship;

c. an unattached disk interposed between each pair of saddles, said disk being slidably positioned on said pin;

d. a stop on said pin at one side of said xeric elements;

e. movable means on the other side of said xeric elements; and

f. means for indicating the amount of movement of said movable means.

2. The hygrometer of claim 1 wherein the edges of said disk is beveled to modify movement of the saddles.

3. A linear action hydrometer comprising:

a. a frame;

b. a bar mounted for linear movement in said frame;

c. a rotatable member mounted in said frame;

d. a bow-spring wire connected at one end to one end of said bar, encircling said rotatable member and thence to the other end of said bar;

e. a pair of xeric elements in face-to-face relationship against the one end of said bar, said xeric elements including:

1. a saddle formed of thin resilient metal;

2. a moisture-sensitive fiber taken from the seed pod of the plant of the genus Geranium, and

3. means for securing the ends of the fiber to the metallic saddle,

f. spring means for biasing said bar against said pair of xeric elements;

g. a disk interposed between the opposed faces of said xeric elements; and

h. means for indicating the amount of rotation of said rotatable member.

4. The apparatus of claim 3 wherein the means for indicating the amount of rotation of said rotatable member is a pointer.

5. The apparatus of claim 3 wherein the rotatable memberis mounted on a taut wire.

6. The apparatus of claim 3 comprising also means for adjusting the diameter of the rotatable member. 

1. A linear action hygrometer comprising: a. a plurality of xeric elements, said xeric elements including a saddle formed of thin resilient metal, a moisture-sensitive fiber taken from the seed pod of the plant of the genus Geranium, and means for securing the ends of the fiber to the metallic saddle; b. a pin for holding a plurality of said elements, said elements being slidably positioned on said pin in face-to-face relationship; c. an unattached disk interposed between each pair of saddles, said disk being slidably positioned on said pin; d. a stop on said pin at one side of said xeric elements; e. movable means on the other side of said xeric elements; and f. means for indicating the amount of movement of said movable means.
 2. The hygrometer of claim 1 wherein the edges of said disk is beveled to modify movement of the saddles.
 2. a moisture-sensitive fiber taken from the seed pod of the plant of the genus Geranium, and
 3. means for securing the ends of the fiber to the metallic saddle, f. spring means for biasing said bar against said pair of xeric elements; g. a disk interposed between the opposed faces of said xeric elements; and h. means for indicating the amount of rotation of said rotatable member.
 3. A linear action hydrometer comprising: a. a frame; b. a bar mounted for linear movement in said frame; c. a rotatable member mounted in said frame; d. a bow-spring wire connected at one end to one end of said bar, encircling said rotatable member and thence to the other end of said bar; e. a pair of xeric elements in face-to-face relationship against the one end of said bar, said xeric elements including:
 4. The apparatus of claim 3 wherein the means for indicating the amount of rotation of said rotatable member is a pointer.
 5. The apparatus of claim 3 wherein the rotatable member is mounted on a taut wire.
 6. The apparatus of claim 3 comprising also means for adjusting the diameter of the rotatable member. 